A) Field of the Invention
The present invention relates to a plant gene regulatory element and its uses, and more particularly to a silencing element for modulating plant responses to pathogens, auxin and ethylene. The invention also relates to transcriptional repressors which specifically binds onto the silencing element of the invention, including a protein referred herein after as “SEBF”.
B) Brief Description of the Prior Art
A variety of defense specific events are induced in plants in response to pathogen infection. Although key components of the signaling cascades are being discovered, few transcription factors that integrate these signals at the transcriptional level have been identified up to date.
PR genes are plant genes that are induced by pathogen invasion. These genes are subdivided into 11 classes. Since PR genes are well characterized, they provide excellent models to study transcriptional regulation of defense genes.
The PR-10 gene family is one of the classes of PR genes. Expression studies have identified cis-acting elements involved in PR-10a gene regulation, a member of the PR-10 gene family. An elicitor response element (ERE) located between nucleotides −135 and −105 is essential and sufficient for elicitor induced expression of PR-10a. PBF-2, a single-stranded DNA binding factor, appears to play a role in activation of PR-10a from the ERE. It has been shown that the presence of the ERE is sufficient for PR-10a activation, removal of the silencing element (SE), located between −52 and −27, leads to further activation, suggesting that SE participates, with the ERE, in the regulation of PR-10a (Matton et al, 1993; Després et al., 1995). However, the exact nucleic acid sequence required for full SE activity has never been given. Furthermore, the identity of the transcriptional repressor specifically binding to the silencing element (SE) of PR-10a is also unknown.
Accordingly, there is a need for an isolated or purified nucleic acid comprising a sequence coding for full of SE activity and to the use thereof for modulating activity of genes, and more particularly genes involved in plant responses to pathogen such as PR-10a gene. There is also a need for methods and genetically modified plants wherein the nucleic acid of the invention has been introduced or wherein the sequence coding for full SE activity has been mutated, deleted, or silenced, thereby modulating the plant defense mechanisms and resistance to pathogens.
There is also a long felt need for a transcriptional repressor that is capable of modulating plant defense mechanisms and resistance to pathogens and more particularly for a transcriptional repressor capable to specifically bind the isolated or purified nucleic acid of the invention. There is also a need for methods and genetically modified plants wherein levels of the transcriptional repressor of the invention have been modulated.
There is a further need for effective methods and compositions to modulate plant resistance or tolerance to pathogens, and/or to modulate plant response to auxin and/or to ethylene.
The present invention fulfills these needs and also other needs which will be apparent to those skilled in the art upon reading the following specification.